1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly, to a method of performing power control in a mobile communication system.
2. Background of the Related Art
Typically, when reverse link data frames are transmitted at a variable data rate, there are two methods for determining a data rate and transmitting the data frames at the determined data rate as follows.
First, the data rate is determined by a terminal. In other words, the terminal starts transmission of a data frame at a minimum data rate. Then, the terminal checks its own communication condition and determines to increase/decrease or maintain the data rate in accordance with communication condition.
Second, there is a second method of determining the data rate of the terminal by scheduling of the base station. That is, the data rate of the terminal is determined according to a strength of a received pilot signal, an available transmission power of a corresponding terminal, and a strength of total received signal power by the base station.
When the data rate is determined by scheduling of the base station, a short frame is used to transmit the data frame at the determined data rate. Therefore, in case that the base station schedules a plurality of data transmissions such that a terminal may transmit a high rate data frame, the high data rate may be increased to a maximum data rate acceptable within a predetermined noise rise limit. Accordingly, the terminal may obtain a great amount of data throughput. As the terminal having the high rate data transmits the data at a high power, low rate data and/or voice data transmission of other terminals in the same sector may be interfered by the high rate data transmission. Therefore, a frame error rate of the low rate data and/or voice data may be significantly increased. The base station may schedule a rate of the high rate data in accordance with the noise signal level and/or interference signal level so that the low rate data/or voice data may not have a significant frame error rate. However, even so the interference may instantaneously increase when a new terminal in the sector including a few terminals being transmitting the low rate data and/or voice data connects with the base station, and requires high rate data service, the base station may accept the high rate data service. If the terminals transmitting the low rate data and/or voice data do not properly reflect changes of the interference raised by transmission of the high rate data, a significant frame error in transmitting the low rate data and/or voice data may be generated.